At present, telephone communication with residential and other telephone subscribers is normally via a telephone line to a local office operated by a service provider, commonly called a local exchange carrier (LEC). The telephone line is usually terminated at the subscriber's location in the form of a pair of wires (called the tip and ring wires). All telephone calls (local and long distance) originated by the subscriber are received by the local central office via this connection. For local calls and long distance (toll) calls within the serving LATA (Local Access and Transport Area), the LEC connects the call to the called party via switching facilities within its serving area. For long distance calls outside the LATA, the LEC is currently required to deliver the call to a long distance carrier, commonly called an inter-exchange carrier (IXC). The IXC routes the call through its switching network to a LEC serving the area where the called party is located. The serving LEC makes the terminating connection to the called party via its local central office.
In addition to tip and ring wires, many subscriber residences and other telephone locations are now served or in the future will be served by other communication systems capable of carrying telephone signals, such as alternate (e.g., toll) telephone signal carriers and wired and wireless cable systems. Alternate telephone signal carrier systems include wired and wireless connections to a central office that is dedicated to carrying local or long distance toll calls.
Some cable systems carry entertainment signals to a residence or other location, and others carry utility information signals away from a residence or other location. Cable systems normally include a home interface unit located at the residence that couples a coaxial cable to pairs of wires that are connected to signal receivers or transmitters located within the residence, such as video tape recorders, television sets, electric and gas meters, etc. The coaxial and other (e.g., optical fiber) cables utilized by cable systems have the capability of simultaneously, bidirectionally carrying a variety of different signals without interference. In most instances, the full capacity of the coaxial and other cables used by cable systems is not utilized by residential telephone subscribers. Significant capability remains available. Proposals have been made to use this additional capacity to carry telephone signals.
Proposals to use alternate telephone signal carrier systems and cable systems have involved the use of a manually operated switching system that allows a subscriber to switch between the normal (local exchange) telephone tip and ring wires and the alternate signal path. Unfortunately, manually operable switches are undesirable. First, they require the subscriber to decide which system to utilize when a telephone call is to be made. Second, such switches require the intervention of the subscriber when an incoming call is received in order to connect the subscriber's telephone instrument to the appropriate signal path. Thus, a need exists for a subscriber telephone diverter switch that connects a subscriber telephone instrument to either of two telephone signal paths, both in an outbound and inbound manner that is entirely transparent to the subscriber and requires no action on the subscriber's part other than using the subscriber's telephone instrument in the normal manner. The present invention is directed to fulfilling this need.